Tuning mechanism



Oct. 8, 1.946.4 A. J. LOMBARDI TUNING MECHANISM Filed Feb. 15,' 1943 .a G. I F

lNvENToR A. J. LOMBARDI BY n ATroRNEY Patented ct. 8, 1,946

Anthony J. Lombardi, Floral Park, N. .Y., assignor to Sperry Gyroscope Company, Inc.,fBrooklyn, N. Y., a corporation of New York Application February 15, 1943, Serial No. 476,011

claims. 1

This' invention relates to electronic apparatus and is more particularly concerned with tuniner mechanism for such apparatus.

In its preferred embodiment the invention will be described as adapted for fine adjustment gang tuning mechanism in electronic apparatus of the hollow resonator type;

For gang tuning a two resonator velocity modulation device, it has become usual to simultaneously vary the input and output electrode spac-v ings in the device. Various ne adjustment ,mechanisms have been suggested, tested and used for gang tuning in this manner. Many of these have proved unreliable in that theyiare not capable of reproducible adjustment, some have poor life due to excessive or uneven wear in the parts, and the most reliable adjustments heretofore known are essentially complicated and require many accurately machined' parts.

It is therefore themajor object of the present invention to provide a novel gang tuning mechanism for electronic apparatus which isy inexpensive, simple in construction, reliable and accurate during repeated tuning cycles, and which has a working` life comparable to the device in which itis employed.

A further'object of the invention is to provide a novel displaceable spherical ball, fine adjustment mechanism for gang tuning in hollow resonator and like electronic devices.v

It is a further object of the invention toprovide a fine adjustment mechanism for gang tuning in a hollow resonator or other electronic device wherein translational movement of an adjustable tuning control is divided in a novel man-1 ner into generally oppositelyl directed Atranslational forces and movements, angularly related to the direction of 'movement of said control and acting to simultaneously displace vtwo tuning members in said device. Preferably these .opposite movements are equal in amount andvat right angles to the driving movement.

A further objectl of the invention is'toY provide a novelv gang tuning mechanism for obtaining accurately tracking input and output electrodev spacing adjustment in a hollowV resonator or like electronic device l Further objects of the invention will presently appear as the description proceeds in connection with the appended claims and theannexed drawing wherein: ,Y y'

Fig. 1 isa vsideelevation partly broken away andV partly in sectionillustrating a-preferred form of my novel gang tuning mechanism;

Fig. 2 is lan' enlarged fragmentary view comprising mainly a section along line 2-2 of Fig. 1;

Fig. 3 is a fragmentary elevation in section illustrating an optional construction in the line adjustment control wherein a tri-ball adjustment is provided;

Fig. 4 is an elevation, partly in section along line 4--4 in Fig. 5, illustrating a further embodiment of the invention; and

Fig. 5 is a plan View broken away and in secttion illustrating details of the tuning mechanism of Fig. 4.

Referring to Fig. 1, which illustrates a velocity modulation device of the two resonator type substantially symmetricalabout axis A-A, a pronged base II of conventional construction provides a sealed closure for one end of a glass tube I2 enclosing a suitable cathode assembly I3. At its other end, tube I2 is sealed concentrically with a relatively heavy annular metal disc I4, the outer diameter of which is about twice the diameter of the tube I2.

A cylindrical metal barrel I5 provides a common side wall for input and output resonator rigidly connected to the flexible annular end wall 25 of chamber I'I by a flanged collar 26 similar to collar 22,

Parallel input grid electrodes 2T and 28 are mounted on collar 22 and wall I9, respectively, and'parallel output grid electrodes 29 and 3l are mounted on wall 2I and collar 26, respectively. The above-described construction, which is representative of a hollow resonator device for which my invention is primarily adapted, is designed so that displacement of either or both discs I4 and 24 generally in the direction of axis A-Aof the device will result in changes in the inputI and/or output grid spacing `because lof the flexibility of walls 23 and 25.

In many devices of this nature it is desirable that'thespacing of both input and output grids -be altered at the same Ytime and by the same amount, and it is' to that-end that the gang tuning mechanism Shown in'Fig, 1 is directed. Y

Intermediate its ends, barrel I5 has rigidly e 3 mounted an external ange 32 to which is secured, as by machine screws (not shown), a heavy metal mounting ring 33. Ring 33 is formed with an external, longitudinally extending peripheral groove 34 for rigidly seating a hollow cylindrical metal guide tube 35 disposed generally parallel to axis A--A. Tube 35 is apertured intermediate its ends to receive a second hollow cylindrical guide tube 3E which is rigidly secured thereto. The axes of tubes 35 and 38 are disposed at right angles, so that a substantially integral T-shaped hollow fitting is provided rigidly secured to ring 33 and having an extension projecting radially outwardly from the device.

While guides 35 and 3S are preferably at right angles, as shown, opposite arms of guide 35 may be made at any desired angle to guide 36 without departing from the spirit of the invention.

Tubes 35 and 33 are internally machined to desired size. Since they are cylindrical, this operation can be accurately and conveniently done. A plurality of spherical balls of the same size are slidably disposed in tube 35, one set 31 being positioned to one side of the axis of tube 36, and the other set 33 being positioned to the other side of the axis of tube 35. While two balls are illustrated in each set, one or any other desired number of balls may be so provided. A spherical ballA 39 is slidably disposed within tube 33 so as to partly project into the interior of tube 35 to contact the two adjacent balls 31 and 38.

Ball 39 is shown as of the same diameter as balls 31 and 3S, but may be larger or smaller as desired. In any event each ball is selected of such size as to accurately nt snugly but slidably within its supporting guide tube.. Preferably, the balls have an outside diameter almost exactly the same as the inner tube diameter so that there is no diametral play. Balls 31-39 are preferably precision-made bearing balls of the type used in high grade ball bearings. Such bearing balls are hardened steel, are accurately spherical, are capable of withstanding extremely heavy radial loads, and are hence admirably suited to the invention.

Outer balls 31 and 33 are contacted by the suitably concaved ends of link pins 4I and 42 which may extend lwithin the opposite ends of tube 35, and pins 4l and 42 in turn have their convexouter ends seated in suitable concave mating surfaces in the ends of coarse adjustment screws 43 and 44 threaded in discs i4 and 24. This in eiect comprises a universal link connection between each outer ball 31, 38 and its associated screw. While pins 4I and 42 are shown as independent members, they may, if desired, comprise universally jointed extensions of the screws.

Tube 35 is internally threaded for adjustably mounting a screw 45 having a reduced shank terminating in a hardened planar face 46 at right angles to the tube'axis and adapted to contact ball 39. A suitable manual knob 48 is provided on screw 45 for convenience inadjust,y

At points spaced 126 on either side of the above-described line adjustment mechanism, flange 33 is engaged at opposite sides by the rounded end tips of relatively coarse aligned adjustment screws 41 and 48 threaded in discs i4 and 24, Similarly, the outer peripheries of discs ,I4 and 24 areinterconneoted 4by three equally spaced strongY tension springs 49 (only one shown);Y V'Springs '49, which ,are parallel to axis` expen'sively. available in quantity.r

A-A, tend to draw discs I4 and 24 toward each other, While the coarse and fine adjustment devices above-described positively oppose the pull of the springs.

In practice, the parts are assembled as shown in Fig. 1, screws 43, 44 and 41, 48 providing coarse adjustments for preliminarily setting the device nearly in operating condition. At this point, the rounded tips of each pair of screws 41, 48 is in engagement with opposite sides of ring 33 and .the fine adjustment parts are in solid contact,

as illustrated. When knob 40 is rotated, screw 45 is translated along the axis of tube 36 to advance driving ball 39 further into tube 35. Such causes the simultaneous and equal outward displacement of balls 31 and 38 in opposite directions, but parallel to axis A-A. This displacement of balls 31, 38 is transmitted through pins 4I, 42 and screws 43, 44 to effect relative separation of discs I4 and 24, thereby causing grid 21 to be displaced away from grid 28 by exactly the same amountand at the same time that grid 3| is displaced away from grid 29. This gang tunes the resonators. When screw 45 is rotated in the opposite direction, springs 49 cause the reverse of Ytheabove operation and reduce the grid spacings simultaneously and equally. I have found that by this arrangement the input and output Vgrid spacing. adjustments track accurately over the tuning cycle life of the resonators.

As discs I4 and 24 are relatively separated or drawn together by action of the iine adjustment mechanism, their relative motion is not exactly parallel, but is rather a 'pivotal displacement fulcrumed at the rounded tips of screws 41, 48. However, the actualdistance moved by the grids during'the entire ne adjustment range necessary ior tuning the resonators is so small that this departure from actual parallelism is negligible For example, in a tube of about the actual 'size' shown `in Fig. 1, the tuning movement range is only about 0.03 inch.

The above-described ne adjustment is very accurate and reliable, and the two 'grid spacings track perfectly during the tuning cycle life. Balls 3?-39 are in substantially point contact only with each other and their associated guide cylinders at all times so that thereV is theoretically no friction, andeven" the small friction which may 4existpractically Ycan be reduced by providing a suitable lubricant in the T-iitting. I have .thus

`vprovided a substantially frictionless mechanism .for converting motion of translation in a given direction tojmotion of translation at right angles thereto in opposite' directions. Precision-made balllbearingslfor the purpose are vreadily and in Furthermore, Vduring repeated'adjustment, the

.ballsn usually. become relatively rotated, thereby "equalizing the wear on each other and the guides. Sincefthe forces acting between ball 39 and.

adjacentballs 31, 38 are radial, the components parallel to the guide axis of guide 35 are small as comparedto the force, so that using a suitable threadat 45 almost any desired fine movement can be obtained. All the parts are in solid oontact without play, and it is important to note thatv thereis little or no frictional wear on the l'pins4I, A42V or the threads by screws 43, 44..

My iine adjustment is inexpensive to make as the only accurate machine operations required are Ireaming -of ,the cylindrical guides, so that considerable `savingsnare leiected ,by the invention.

f In the form' of the invention shown in Fig; 3,

the reduced inner end of screw rod 135 abuts against ball 39 as in Fig. l. However, only one ball 31, 38 is here used in each set, pins 4I, 42 being made correspondingly longer.

Referring now to Figs. 4 and 5, the ne adjustment mechanism is illustrated as embodying a self-contained subassembly mounted in a cylindrical block 55 which is removably mounted in a suitable socket 5S integral with ring 33, as by set screw 57.

Block 55 is formed with lan axial bore 58 threaded at 59 for rotatably mounting adjustable screw 6l. Intermediate its ends and disposed to clear socket 56, block 55 is formed With a pair of aligned radial bores 62 and 63 smaller than bore 58. Thefinner end of screw 6! is a planar face 54 at right angles to the axis of block 55 assembly than might be expected from simply reducing their diameters.

As Inanychanges could be made in the above construction and many apparently widely different embodiments of this inventio-n could be v made Without departing from the scope thereof,

in contact with a spherical ball 65.Y Ball 55 in turn is disposed i-n surface Contact with two smaller spherical balls 66 and 61 in bores 62 and B3, respectively. Link pins 4I and 42 contact balls BSand G1 similarly to the structure shown in Fig. l.

Bores 53, S2 and 53 are vcylindrical guides which may easily be accurately machined to size for slidably receiving the respective balls, as in Fig. 1. Preferably, the outer end of each bore 62 and 63 is slightly deformed, as by a punch prick as indicated at 68, to limit radial outward displacement of balls E6 and 61.

When knob 6B of screw 5I is rotated in one direction, face 64 is displaced along the axis of bore 58 to displace ball 55 and force balls 66 and 51 radially outwardly, simultaneously and over equal distances. The ne adjustment otherwise operates exactly as above-described in Fig. 1. The necessary degree of movement required for resonator tuning is so small that limit stops 68 do not interfere with tuning over the entire normal range. For further limiting the range of adjustment, a stop collar 69 may be provided on screw 5I for limiting axial advance of screw 6l within block 55.

A particular advantage of the construction shown in Fig. 5 is that the sub-assembly on block 55 may be assembled and handled as a unit, and

mounted for operation in the device, without dan-v ger of any of the balls dropping out. In assembly, ball 65 is dropped into bore 58, with screw 6| retracted. Then balls 66 and B1 are introduced into their respective bores through bore 58, and screw 6l advanced until the balls Contact and no ball can escape entirely from its associated bore. Also, the balls 66 and 61 being smaller than ball 65, I nd that as a practical matter there is considerably less friction in the axial bore, a spherical fball slidable in each of said radial bores, each of said balls being of substantially the same diameter as its respective bore with the balls in said radial bores being substantially smaller than and adapted to contact said rst ball, the size differential between the balls in the radial bore and the ball in the axial bore tending to ensure that the latter-named ball is conined to the axial bore during its operative travel, and means for adjusting said rod to effect simultaneous outward displacement of the balls in said radial bores.

2. The gang tuning apparatus defined in claim i, wherein said balls in said radial bores project outwardly of said support during said adjustment.

3. The gang tuning apparatus dened in claim 1, including stop means for limiting adjustment of said rod.

4. The gang tuning apparatus dened in claim l,Y including stop ,means limiting outward displacement of said balls in the radial bores.

5. In gang tuning apparatus for an electronic device, a substantially T-shaped guide, a spherical ball slidably disposed in each arm and a third spherical ball slidably disposed in the stem of said guide, the arms and stem of said guide each having an internal diameter equal to the respective balldisposed therein with the ball in said stem being larger than each of the other balls and in contact therewith, the size differential between the balls in each arm and the ball in the stem tends to ensure that the latter named ball isfconned to the stem during its travel, and means in said stem for displacing the ball therein for eecting simultaneous and opposite outward displacement ofk the balls in said arms.

ANTHONY J. LOMBARDI. 

